Monitoring soil contamination over large areas, long periods of time possible thanks to geophysical measurements

February 21, 2013

Large amounts of industrial contaminants, such as mineral oil, chlorinated hydrocarbons and heavy metals, are hidden in the soil and ground water across Europe. Until now, there was no easy way of mapping their distribution and follow their development in the ground. Under the SoilCAM project, funded by the EU, scientists have explored a combination of methods to gain a reliable and accurate understanding of the physical, chemical, and biological behaviour of these soil contaminants. These methods could eventually be used to study the distribution and monitoring of bioremediation and geo-chemical processes over a long period of time.

"By improving our understanding of how the biochemical and geological processes are interlinked and driven by the boundary conditions, such as rain and temperature, we are able to suggest new and improved ways of combining methods in order to get a better control of contaminated sites," explains Helen French, project coordinator based at Bioforsk, the Norwegian Institute of Agricultural and Environmental Research, at Ås outside Oslo. This system has, so far, been tested at Oslo airport, where the challenge was to monitor pollution from de-icing chemicals used on aircrafts and runways in winter. It has also been tested in a second testing site is in Trecate, Italy, where scientists monitored a historical oil spill from petroleum wells, dating back from 1994.

In addition to combining existing instrumentation, scientists developed new technologies, for example a prototype of an ultra-fast complex resistivity meter for borehole and surface investigations, called Polares. It is designed to relate soil pollutants to certain geophysical parameters such as the electrical conductivity and induced polarisability. The innovative aspect of Polares is the possibility to make observations at high frequencies, which gives a better potential to detect soil pollution, as more date is available over a wider frequency span. "Induced polarisation clearly is the most promising geophysical method to track contamination," Andreas Pfaffhuber, head of Geosurveys sections at the Norwegian Geotechnical Institute (NGI) in Oslo, Norway, tells youris.com.

Remote access to some of this information as well as modeling with new geophysical software for 2D and 3D data processing as well as solute transport modelling, could ultimately help provide a system for optimised monitoring with classical sampling techniques. Experts recognise that this approach constitutes progress compared to previous technologies. "By combining different mapping and monitoring techniques, the SoilCAM project has managed to provide a fuller picture of the situation under the soil's surface as well as the substructures," says Torleif Dahlin, professor of engineering geology at Lund University, Sweden. Indeed, he adds: "By using traditional methods mapping the subsurface at certain points, you cannot tell how the permeability of the underground structures is distributed. This makes it very difficult to know how contamination moves and affects the soil and groundwater."

Thus, this approach can also provide an early warning system showing when there are large changes in hydraulic or contaminant situation, according to French. "We hope – within a couple of years – to be able to offer these as practical tools for providing early warning systems and better spatial coverage," she says, "hence avoiding or reducing [contamination] at sites affected by pollution from heavy industry, building sites and transport infrastructure."

Before this technology can be more widely applied, Pfaffhuber warns, prior testing of each site is key: "as it is still not 100% clear, how geophysical properties and contamination interact, there will always be a certain remaining risk that the method won't work at the client's particular site." He sees potential additional applications, for example, in the management of ground water resources, tailing dams, leakage through river dams, landslides particularly in the case when permafrost thickness is the cause. "Yet the likelihood for such an implementation," he concludes, "is largely determined by the industry's acceptance of [what would be for them] an unknown technology."

Related Stories

New methods might allow polluted sites to be investigated and monitored long term at significantly reduced costs. Authorities and those who have to remediate polluted sites in Europe might therefore be able to save costs ...

To meet the needs of a growing population and to provide it with a higher quality of life, increasing pressures are being placed on the environment through the development of agriculture, industry, and infrastructures.

The poet William Blake once wrote that we could "see a world in a grain of sand." Today, environmental engineers are seeing the world beneath the surface through a greener part of nature: the trunks and branches of trees.

CSIRO scientists have developed a revolutionary technique for the rapid on-site detection and quantification of petroleum hydrocarbons (commonly derived from crude oil) in soil, silt, sediment, or rock.

Land contaminated with substances in or under the land can be potentially hazardous to health or the environment. However, in many cases there is minimal risk from living or working on contaminated ground and many c sites ...

Recommended for you

Five million years ago, the Colorado River met the Gulf of California near the present-day desert town of Blythe, California. The evidence, say University of Oregon geologists, is in the sedimentary rocks exposed at the edges ...

Pressure, temperature and fluid composition play an important role in the amount of metals and other chemicals found in wastewaters from hydraulically fractured gas reservoirs, according to Penn State researchers.

Pioneering work being carried out in a cave in New Mexico by researchers at McMaster University and The University of Akron, Ohio, is changing the understanding of how antibiotic resistance may have emerged and how doctors ...

(Phys.org)—A team of researchers with the European Commission's Joint Research Centre and Google Switzerland has combined historical data with modern mapping engines to produce high-resolution maps of the world's surface ...

The ice sheet covering Greenland is four times bigger than California—and holds enough water to raise global sea-level more than twenty feet if most of it were to melt. Today, sea levels are rising and the melting of Greenland ...

0 comments

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.